DESCRIPTION This application studies small synthetic peptides which could inhibit Abeta aggregation or potentially promote fibril dissolution. These peptides are based on Abeta, the Abeta binding binding domain of transthyretin and from Abeta and fibril binding screens of a random peptide library. The specific aims are: Aim 1. To study inhibition of Abeta fibril formation and stages of fibril assembly by Abeta binding peptides selected from a peptide library. A set of candidate peptides has already been identified and preliminary data show that some of these peptides block Abeta aggregation. Aim 2. To identify, from random peptide libraries, Abeta binding peptides which dissolve preformed abeta fibrils. Aim 3. To analyze effects of all Abeta inhibitors found in aims 1 and 2 on Abeta accumulation and cytotoxicity in cultured canine and human cerebrovascular smooth muscle cells.